PURPOSE: To make an amount of sticking toner proper in both graphic printing and line drawing printing by exposing parts, excluding a plane edge, one more time by means of a second exposure light source only in the case of picture information with equal or more prescribed area.
CONSTITUTION: For an optical image corresponding to picture information, the entire picture information is written on a uniformly electrified, photoconductive insulated body 2 by means of a first exposure light source 4 based on data from a control part 3. In the case of the entire picture information with equal or more prescribed area, the parts irradiated by the first exposure light source 4, excluding the plane edge of the light source, are irradiated and exposed one more time by the second exposure light source 5 based on data from the control part 3. Since potential exerted on the edge of the optical image plane is almost equal to the entire potential excluding the potential of the edge, the edge effect in toner development is prevented. On the other hand, in the case of the entire picture information with equal or less prescribed area, exposure by means of the second exposure light source 5 is not carried out. Thus, even in the case of line drawing printing, toner is not developed excessively.
HORIKOSHI YUZO
TAMURA HIROMI
SEKIGUCHI KUNIO
KUSABA HITOSHI
